1. Field of the Invention
This invention relates to a structure of a clutch plate of an automatic transmission principally used for controlling the transmission of driving force in a vehicle, and relates to a method of producing it.
2. Description of the Prior Art
As shown in FIG. 9, there has been known a conventional structure of a clutch plate as disclosed in, for example, Japanese Utility Model Application Early Laid-Open Publication No. Sho 62-172826.
In this type of clutch plate structure, liquid binding materials 3, 3 are applied to both side portions 2, 2 of a metallic core plate 1 shaped substantially like a disk, and facings 4,4 used as a friction member are attached thereto. The facing 4 is made of base paper and has the shape of a laminar disk.
In this clutch plate 5, as shown in FIG. 10, generally, the grease of the core plate 1 formed by draw-molding is removed with a detergent, and thereafter etching treatment of the core plate 1 is conducted chemically with a hydrochloric acid or nitric acid treating agent, so that coarse grounds having greater adhesive strength are formed on the side portions 2, 2. After that, the liquid binding material 3 is applied to the side portions 2, 2 of the core plate 1 on which the etching treatment has been completed.
In order to heighten durability, an impregnant is impregnated into the base paper of the friction member, and then the friction member is punched to be shaped substantially like a disk, and the facings 4, 4 are formed. Thereafter, the facings 4, 4 are attached to the side portions 2, 2, respectively, with the binding material 3. After the adhesion has been completed, the clutch plate 5 is obtained via drying, sizing, and grooving processes.
In the clutch plate 5 thus constructed, the grease of the core plate 1 is removed with a chemical agent, and thereafter etching treatment of the core plate 1 is conducted, and thus the core plate 1 is chemically coarsened. With the satisfactory adhesive strength of the binding materials 3, 3, the facings 4, 4 adhere to the side portions 2, 2.
After this treatment has been completed, the facings 4, 4 are attached to the side portions 2, 2 by means of the binding materials 3, 3. In this known clutch plate, a chemical material, such as a chemical agent and a treating agent, is required for a grease removal operation and etching treatment. However, there is a fear that, since the treating agent is intensely deteriorated with the passage of time, the deterioration thereof will make uneven the quality of a treated surface at the etching treatment, and the adhesive strength will be varied.